This invention relates generally to sulfurized phenols which are useful as antioxidants and more specifically to liquid, partially sulfurized, hindered phenol compositions having reduced volatility and chlorine content.
Liquid, partially sulfurized, hindered phenol compositions having reduced copper corrosion are disclosed in a copending application filed concurrently herewith. These compositions contain at least about 30 weight percent of unreacted phenols. These unreacted phenols are more volatile than the sulfur bridged phenol portion of the mixture and tend to be vaporized when the mixture is used in lubricating oils during high temperature operation. We have now found that reacting the mixture with formaldehyde not only reduces the volatility of the unsulfurized phenols but, surprisingly, results in a product mixture which also has a reduced chlorine content.